Almost every homeowner has experienced the problems resulting from a clogged drain pipe under a sink. The clogging usually is caused by fats, soaps, and food particles which collect in the drain pipe and eventually completely close the pipe to gravity flow from the sink. Various methods and devices have been employed with varying success to remove the clogging material and restore the drainage flow. Mechanical devices, such as a drain auger (commonly called a plumber's snake), or a rubber plunger, are normally used to unplug the drain. Powerful solvents containing alkali are frequently poured into the drain to dissolve the clogging material. More recent systems involve the use of pressurized hot or cold water (from the tap at the sink) through a side inlet in the U-tube section of the drain pipe. These systems, of course, require some means of applying the force of pressurized water to the upstream side of the clogging material without permitting any of the pressurized water to flow upwards into the sink. Some prior art systems have employed a valve built into the drainage line which can be turned to provide free flow of water from the sink or to close off the flow to or from the sink and at the same time open flow from a side inlet through which pressurized water can be introduced to force the clogging material to move downwardly in the drain pipe to a sewer line. Typical of such systems are those disclosed in U.S. Pat. No. 215,928 to Hutchinson; U.S. Pat. No. 734,682 to Doyle; and U.S. Pat. No. 1,938,064 to Carmine. These systems, however, are deficient in that they introduce into the drain line obstructions which may cause clogging to occur more easily than would be the case if the drain line had no unclogging devices at all.
It is an object of this invention to provide an improved system for opening clogged drain lines from sinks. It is another object of this invention to provide an improved system that will prevent any possibility of contaminating backflow from the drain pipe into the purified water supply. Still other objects will appear from the more detailed description which follows.